Separation of fatty acid compound mixtures



-STORAGE INVENTORS HEAT EXCHANGEFL Sept. 4, 1962 STRAGE- HANS WALDMANN WERNER STE/N BY @ugm DMZ-few ATTORNEJS 3,052,700 Patented Sept. 4, 1962 Fire 3,052,70il SEPARATKQN OF FATTY ACID (IOMPQUND MIXTURES Hans Waldmann, Dusseldorf-Ellen and Werner Stein, Dusseldorf-Holthausen, Germany, assignors to Henkel & Cie. G.rn.b.H., Dusseldorf-Holthausen, Germany, a corporation of Germany Filed June 24, 1959, Ser. No. 822,663 Claims priority, application Germany July 3, 1958 8 Claims. (Cl. 260-419) This invention relates to improvements in the separation of mixtures of fatty acids. It more particularly relates to the separation of these mixtures into components of different melting points.

Fatty acids of natural or synthetic origin are usually obtained by way of mixtures of fatty acids, the individual components of which differ from one another by their melting points. Separation of these fatty acids from their mixtures has hitherto entailed certain difficulties, disadvantages and drawbacks. Such separation was usually accomplished by the use of organic solvents, separation by filtering, use of hydraulic presses, etc.

It has additionally been suggested in US. Patent No. 2,800,493 to efiect the separation of fatty acid mixtures into their components or component cuts by forming a dispersion of the fatty acid material in an aqueous solution containing a surface-active material at a temperature at which the mixture contains solid and liquid components. In this dispersion, the surface-active material serves to wet the surface of the particles of the solid fatty acid or ester and displace the liquid acid or ester therefrom, so that there results a continuous aqueous phase with discrete separate particles of the solid and liquid components. Thereafter, the dispersion is separated by a layer formation into a specifically heavier phase composed of the surface-active material containing suspended particles of the solid component and a specifically lighter phase composed of the liquid components. The separation of the dispersion into the two phases is then effected by centrifugal action, as for example in a centrifugal separator of the imperforate type.

When the dispersion is subjected to centrifugal action in an imperforate centrifuge, the aqueous phase containing the suspended solid fatty particles pass over as the specifically heavier fraction, and the liquid fatty particles Separate as a specifically lighter fraction.

The advantages of the aforesaid procedure is that the separation is extremely clean-cut with the solid fatty particles being substantially free from the liquid fatty component. In addition, the physical effecting of the process is highly efiicien-t and economical, being excellently suited for commercial operation with high throughput efficiency and low cost. The disadvantages encountered with the liquid or solid separation, as for example with filtration, etc., are thus avoided.

However, the separation as above described suffers from the drawback that it does not afford the possibility other than by varying certain operating conditions, i.e. the cooling rate, the separating temperature, the nature and quantity of liquid organic compounds or their mixtures added, to alter or influence the consistency of the mixture to be separated and the composition of the solid and liquid components. In other words, the use of the aqueous phase to effect the separation does not have any effect on the dissemination of the substances of differcnt melting points in the solid and liquid phases intermixed in the starting material. This distribution is very important with respect to the separation effect achieved and above all, the composition, i.e. state, of the solid fatty particles is critical with respect to this effect. That is, in the crystal lattice of the solid components there are to be inserted as few liquid component particles as possible, and also, as few liquid component particles as possible are to be occluded by the crystals. As is well known, fatty materials possess a substantially poorer crystallization capacity than many other organic compounds. The higher melting compounds, present in a molten mixture of fatty materials having different melting points, crystallize out very slowly and at that they have the tendency to a higher degree than many other organic compounds to build into the crystal structure 10W- er melting materials or to incorporate mechanically such particles in the course of the crystal growth.

An object of this invention is an improved process for the separation of fatty acid and fatty acid ester mixtures into components of different melting points.

The foregoing, and still further objects of the inven tion, will become apparent from the following description read in conjunction with the drawings, in which FIG. 1 is a diagrammatic vertical section of an embodiment of a cooling apparatus, useful in the practice of the invention;

FIG. 2 is a diagrammatic vertical section of a further embodiment of a cooling apparatus, useful in the practice of the invention; and

FIG. 3 is a diagrammatic vertical section of a further embodiment of a cooling apparatus, useful in the practice of the invention, in which the cooling vessels also serve as intermediate containers.

In accordance with the invention it has now been found that in the process of separating mixtures of fatty acid materials, the components of which differ from one another by their melting points by forming a dispersion of the fatty acid material in an aqueous solution containing a surface-active material at a temperature at which the mixture contains solid and liquid components and whereafter the dispersion is separated by a layer formation into a specifically heavier phase composed of the aqueous solution of the surface-active material containing suspended particles of the solid component and a specifically lighter phase composed of the liquid components, particularly favorable dispersion mixtures of solid and liquid components are obtained if the starting fatty acid material is cooled from a higher temperature to the separation temperature in stages, said cooling stages being at least once interrupted by an intermediate stage in which substantially no cooling takes place.

The ratio of the time of stay, i.e. duration, of the material in the intermediate stage to the time of stay of the material in the cooling stage, in accordance with the invention, may within wide limits vary within the range of about 200:1 to 1:200.

In many cases, fatty material mixtures are to be processed, whose higher melting components still possess, for fatty materials, good crystallization tendencies. These maybe processed according to the usual separation processes for liquid and solid materials. Such mixtures are, for instance, mixtures of stearin and olein from which the olein may be pressed off after crystallization of the stearin. According to Bailey: Industrial Oil and Fat Products," 1945, New York, page 873, paragraph 4, the components of such a mixture may be separated by effecting the crystallization of the higher melting component. In processing such mixtures, whose higher melting components have good crystallization tendency, it is recommended in accordance with the invention that the length of the time of stay of the materials in the intermediate stage should be at least as great as in the preceding cooling stage, and preferably the time of stay of the material in the intermediae stage should amount to a multiple of the time of stay in the preceding cooling stage. The ratio of the time of stay of the material in the intermediate state to the time of stay of the material in the cooling stage may, for example, lie within the range of 4:1 to

3 200:1 and preferably lies within the range of :1 to 50:1.

For the cooling of the fatty acid mixtures, heat exchange-rs are used, in which the walls which serve to effect the heat exchange are kept free from deposits of solid fatty materials. This is accomplished by passing the fatty acid material adjacent and in contact with walls serving for the heat exchange at a high flow speed rate or under conditions of high turbulence, so that through the shearing forces occurring at the cooling surface any deposits which are formed are torn away. There are particularly preferred as heat exchange units the so-called scraper coolers. Here one deals with cylindrical cooling devices, in which the cooling surfaces, which come into contact with the fatty material mixture, are kept the free from deposits of solid fatty materials by means of moving scrapers or shavers.

The depositing of solid fatty materials on the cooling surfaces may also be decreased or in fact entirely prevented if the fatty materials are passed through the coolers in form of a dispersion in aqueous phase and, if necessary, in an aqueous wetting agent solution. In this situation, the fatty materials are present in form of small droplets which are entirely surrounded by aqueous phase, and thus the possibility of a direct contact of the fatty materials with the cooling surface is strongly decreased. In order to avoid in the heat exchanger, at the lower temperatures, freezing of the aqueous phase or a separation of the substances dissolved therein, it is desirable to add materials to the aqueous phase which reduce the freezing point of water. Suitable for this purpose are inorganic salts and above all organic Water-soluble solvents, particularly if the latter are only diflicultly volatile. Examples of such solvents are the polyvalent alcohols or their water-soluble ethers, as for example ethyleneglycol, glycerin, propylene-glycol, butyleneglycol, polyglycolene, polyglycerines, etc.

Suitable raw materials for the practice of the invention are carboxylic acid ester mixes and fatty acid mixes of both natural or synthetic origin.

Natural carboxylic acid esters are predominantly fatty acid esters and particularly glycerides, such as are obtained from the fat of vegetable and land and marine animals. Examples of the various types of vegetable fats include coconut oil, palm oil, olive oil, soya bean oil, linseed oil, wood oil and rapeseed oil. Examples of the various types of fats obtained from land animals include beef fat, hog fat and bone fat. Examples of the various different types of fats of marine animals include whale oil, menhaden oil, cod liver oil and herring oil.

Among the natural carboxylic acid esters, which con- I tain alcohols other than glycerine as the alcohol compo- .nent, there may be mentioned, for example, sperm oil,

which in addition to glycerides also contains fatty acid aliphatic alcohol esters as well as the wax esters.

In connection with the esters of fatty acids, the alcohol component thereof may be derived from monoand polyvalent, preferably from monoto tri-valent, alcohols.

.The mono-, diand tri-glycerides and the esters of fatty acids and fat alcohols are of particular technical interest.

However, esters of fat alcohols and monoor poly-basic carboxylic acids having from 1-5 carbon atoms in their molecules may be used as starting materials in accordance with the invention.

In addition to glycerides, any other desired ester combination may be used, such as for example are used as softeners, which may be produced synthetically.

When the ester mixtures contain solid as well as liquid components at a given temperature, it is often of industrial importance to separate the mixture into components of different melting points, as for example in the winterizing of edible oils, the separation of hardened fats, the removal of solid constituents from softeners and the separation of isomeric phthalates, etc.

Fatty acid mixes of natural origin are those which are obtained from the naturally occurring carboxylic acid ester mixes mentioned above. The esters may be split with the aid of water or steam or may be saponified with the aid of caustic, while the fatty acids may be liberated from the resulting soaps with the aid of acid. Fatty acid mixtures of synthetic origin may be those obtained, for example, by the oxidation of natural or synthetic parafiins and the isolation of the fatty acids from the oxidation mixture, or may be obtained by the oxidation of alcohols, such as is for example practiced in the hydrogenation of carbon monoxide. Furthermore, the synthetic mixtures may be obtained by the oxidation of products which are obtained from the addition of carbon monoxide and hydrogen to olefins, resulting in fatty acid mixes well suited to separation by the application of the process in accordance with the invention.

The fatty acid mixtures to be processed according to this invention may preferably contain as main components fatty acids of 6-36, preferably 10-28, carbon atoms in their molecule. If the ester mixtures are containing as carboxylic acid components fatty acid radicals, these radicals may be derivated from fatty acids of the same molecular size.

All the above mentioned materials are generally obtained as mixtures containing components of varying melting points. These materials are of industrial importance, and it is generally necessary to separate the mixtures into components of different melting points for further use.

The invention, however, is not limited to the specific, above enumerated mixtures, but is applicable to all similar mixtures regardless of their source of procedure for obtaining the same, as would be obvious to the skilled artisan, since the separation is physical in nature.

The drawings exemplify illustrated embodiments of cooling apparatus usable in the practice of the process in accordance with the invention, without it being intended, however, to limit the application of the novel method to the particular heat exchanger or heat exchanger storage container arrangement there depicted.

Referring to the diagrammatic representation of the cooling arrangement, as illustrated in FIG. 1, in operation, the starting material to be cooled enters into the cylindrical heat exchanger 11 at the connection 15. The cooling agent enters into the exchanger at 14 and leaves the cooling jacket at 13. The starting material to be cooled passes through the cylinder 11, whose inner wall is kept free of deposits by means of a rotating scraper 12, which takes the form of a screw in the embodiment shown in FIG. 1. After the desired cooling has been effected, the starting material passes through the pipe line 16 into the intermediate container 17, from which it leaves at 18 and passes from there into the next cooling stage. As the intermediate container 17 may serve any desired container. It may be provided with guideplates or other immovable or mova-ble interior structures, if desired. In the embodiment shown in FIG. 1 there is provided a movable screw, by means of which the material is stirred thoroughly. The stirring gives rise to shearing forces which serve to promote the crystallization. In place of the container 17 there may also be used the construction which is shown in FIG. 2. This construction consists of a cylindrical container 20 provided with inlet and outlet connections 21 and 22, respectively. In the container, stationary plates 23 are arranged perpendicular to the cylinder shaft, which plates are provided with an opening in the middle thereof, through which the revolving shaft 24 passes' On the revolving shaft 24 there are arranged circular discs 25, so as to alternate with the stationary plates. The fatty material is forced between the revolving and the stationary plates and thereby exposed to particularly strong shearing forces. However, the method can also be effected employing in the intermediate containers very simple stirring devices. Such an arrangement is shown in FIG. 3.

Additionally, the containers 31 and 32 in FIG. 3 serve simultaneously as intermediate containers and storage containers and are provided with the simple stirring devices 34 and 35. Finally, one may employ as the intermediate containers pipe lines of suitable volume, which for instance may even [be ccastructed as pipe coils.

If the temperature of the starting material as supplied lies very much above the temperature at which the crystallization begins, then the cooling down of the starting material to the temperature at which crystallization begins may be effected in any manner desired. The process in accordance with the invention starts with the beginning of crystallization. The heat extraction during the course of the cooling process may take place in any manner desired. Thus, for instance, the heat extraction may be, except for the intermediate stages, uniform- 1y distirbuted over the entire cooling process. However, the heat extraction may be regulated so as to be particularly great at the beginning or at any point in the course of the cooling process, or at the end of same. The particular variation or sequence used depends mainly on the type and the crystallization characteristics of the mate rial to be processed.

The start of the crystallization is initiated earlier if the starting material contains small amounts of crystals, which have either been left in the starting material because of an incomplete melting of same, or if some crystals have been recycled fromlater cooling stages into the container or vessel containing the material.

Because of the low crystallization velocity of fatty materials, the crystallization in general is not completed when the material leaves the heat exchanger. 'It is completed in the intermediate stage, in which no further heat extraction takes place. The vessel, in which the material to be cooled is maintained during the intermediate stage, may be insulated against any possible heat exchange with the suroundin-gs. In the intermediate stage there may occur through the liberation of heat of crystallization a heating of the material. This increase in temperature is not, however, in any way attributable to heat absorption from the environment. The material in the intermediate container may under certain circumstances be supplied with heat. In that instance, the quantity of heat supplied is preferably so regulated that it is smaller than the heat quantity drawn ofl in the preceding cooling step. However, it is also possible to supply in the intermediate stage more heat than was drawn 01f in the preceding cooling step. This special situation should arise, generally speaking, only when the heat balance of the remaining cooling steps has to be regulated so that the starting material is not cooled off to below the separation temperature.

The number of cooling steps to be connected in series should be at least two, but it may be considerably higher and may be, for instance, up to 5200 series-connected steps. After the last cooling step, no further intermediate stage need be arranged.

It has been expressly shown, and this is an essential object of the invention, that the cooling of the starting material to be separated may be attained both as to apparatus and process when the starting material is led through a series of stages, in which the material is passed in a circular course from a storage container, which simultaneously serves as intermediate stage, through a heat exchanger and back into the storage container. Just as in the device, shown in FIG. 1, the ratio of the capacity of the heat exchanger and intermediate vessel has to be proportional to the ratio of the duration of stay, so also in this device the volume ratio of the material present in .the storage vessel to the capacity of the heat exchanger must correspond to the ratio of the duration of stay.

A device suitable for the carrying out of this variation of the process in accordance with the invention is shown in FIG. 3. The material to be cooled is in the storage vessel 31, which is provided with the stirrer 34. A pipe line leads via the distributor system 36 consisting of pipe lines and valves to the heat exchanger 30, and from there via the distributor system 37 consisting of pipe lines and valves back to the storage vessel 31. When the material in storage vessel 31 has reached the desired temperature, then the material is conducted by changing over of the valves of the distributor system 36 via the pipe line 38 for further processing. In the meantime the storage vessel 32 is filled with the material, which is conducted in a circular course via the distributor system 36, the heat exchanger 30 and the distributor system 37, and is thereby cooled oil.

Insofar as the screw worms, shown in the cooling and intermediate vessels according to FIG. 1, do not suffice for the transportation of the material, special conveyor devices, such as for instance pumps of the most varied constructions, are to be provided. This is advisable, above all, in the apparatus according to FIG. 3, where pumps may be arranged for instance between the two storage vessels 31 and 32 and the distributor system 36, between this distributor system and the heat exchanger 35) and/or between this heat exchanger and the distributor system 37.

Conveniently, the size of the storage vessels and the capacity of the heat exchanger and/or the temperature of the cooling agent passing through the heat exchanger is so regulated that there is always required for the reaching of the separation temperature as much time as for the emptying of the other vessel, whose material content is to be passed to the final separation. If the storage vessel running without load is then filled with newly supplied starting material, then the small quantities of solid carboxylic acid ester particles, which still adhere as a residue of the previous charge to the walls of the storage container or which are still in the lines and in the heat exchanger, act as seed crystals and thus promote, i.e. accelerate, the crystallization of the higher melting constituents of the newly fed charge.

Of course the heat exchanger and storage vessel may be arranged for a longer time of stay of the material in the cooling step than in the intermediate stage. The time of stay of the material in the cooling step may, for instance, amount to the 4-20O fold, preferably 10-50 fold, the time of stay in the intermediate stage. It is also possible that heat may be supplied in the intermediate stage.

This variation of the first described process is, above all of advantage for the processing of dil'iicultly crystallizable fats, particularly for some fatty acid triglycerides. Through the increased time of stay in the cooling step, the formation of the first crystals is accelerated. Therefore, it becomes advisable, with the crystallization just starting, to slowly withdraw heat. The slow heat-withdrawal may be attained through a correspondingly weak cooling in the cooling step and/ or when the material is passed through the intermediate stage, supplying in the intermediate stage a part of the heat which has been withdrawn in the cooling step.

The cooling of the starting material, employing a longer time of stay in the cooling step than in the intermediate stage, may be employed when a relatively narrow range of the total temperature decrease is to be effected. This range may, for instance, amount to less than 1 C. but it may also extend to 5, 10 or 20 C.

If, however, a part, preferably 10-50%, of the material to be separated from the starting material as higher melting component has solidified, then one may switch to the mode of operation in which the time of stay in the intermediate stage is greater than in the cooling step.

The mixtures thus obtained of solid and liquid constituents of the starting material are now further processed in the manner known per se. Insofar as these mixtures were not already during the cooling dispersed in an aqueous phase, they must be dispersed in a manner known per se and then the dispersion separated into the two phases.

The separation of the dispersion of the fatty acid mixture may be effected, for example, in certain cases merely by allowing the dispersion to stand, whereby the upper phase of the liquid portion of the fatty acid mixture forms along with a lower phase containing the aqueous solution with the dispersed particles of the solid component of the fatty acid mixture. By decanting the layers, products may be very simply recovered. Preferably the dispersion is separated into layers by centrifugal action, employing therefor centrifuges of the imperforate type.

The process of the invention makes possible for the first time a slow crystallization and one which is, above all, adjustable to any specific fatty acid mixture. As a result of the process there is avoided any undesirable after-crystallization which would otherwise occur in the further processing of the mixture and which would act to change in uncontrollable manner the composition of the solid and of the liquid components of the mixture. The results of the process are very surprising insofar as the same results are not obtained even with slow cooling, employing the same cooling period as in the process in accordance with the invention. A further and very surprising advantage of the process in accordance with the invention consists therein that in the centrifuging of the dispersions obtained in accordance with the invention there is observed an essentially easier transition of the oil droplets dispersed in the aqueous phase into the coherent oil phase than is the case in dispersions in which the cooling of the starting material supplied was effected in another manner.

The following examples are given for the purpose of illustration and not limitation:

Example 1 80 kg. technical lard (iodine number=63.4) were melted down in a vessel equipped with stirrer of stainless steel by heating to 50 C. Thereafter the fat was cooled by pumping the same through a circular course, which consisted of a storage container and a scraper cooler having a 4-liter capacity and an 0.17 m. cooling surface. The volume ratio of fat in the scraper cooler and fat in the storage container including the pipe line amounted to about 1:20. The scraper cooler was cooled with tap water having a temperature of 13 C. The temperature of the fat was measured in the storage container, and there was recorded the following cooling curve:

Temperature,

After reaching the lowest temperature, the fat was left for two hours at 20 C. and then dispersed in an aqueous wetting agent solution, which contained dissolved in solution 0.3% alkylbenzolsulfonate (alkyl from tetrapropylene) and 4 weight-percent sodium sulfate. The weight ratio of fat to wetting agent solution was 1:15. The emulsion was then slowly passed through a stirring vat, in which it was kept in motion by rotating a worm, and was passed from the vat into the centrifugal separator of the imperforate type. In the centrifuge, the dispersion was separated into a lighter oil phase and into a heavier aqueous phase having therein dispersed the solid fatty particles. The aqueous phase was heated in a heat exchanger to a temperature at which the solid particles were completely molten, and thereafter the liquid higher-melting fat fraction was separated from the aqueous phase in a plate centrifuge. There were obtained 61.6 kg.=77 weight-percent of the original charge in lower-melting fat components (iodine number 71.7)

18.4 kg.=23 weight-percent of the charge in higher-melt ing fat components (iodine number 36.0).

When the same starting material was continually cooled down over a period of 8 hours, but otherwise under the same conditions as above described, there was obtained a clearly recognizable slower separation of the oil droplets from the dispersions in the centrifugation step.

Example 2 As starting material there was employed a Sumatra palm oil (iodine number=50.4), from which there had been removed small amounts of free fatty acids by a vacuum-steam distillation. (This process has been described by Wecker, German Patent No. 397,332). 50 kg. of the treated palm oil were cooled under substantially the same conditions as described in Example 1 (volume ratio 1:13). The cooling took place over a period of 6 hours, the fat being cooled from 50 to 20 C. Thereafter, the mixture of solid and liquid fat components thereby obtained was dispersed in the manner described in Example 1. The following fractions were obtained:

40 kg.= weight-percent lower-melting components (iodine number 56.8)

10 kg.=20 weight-percent higher-melting components (iodine number 25.0).

The process was repeated, but in this case the starting material was slowly and continuously cooled from 50 to 20 C. The following fractions were separated:

80 weight-percent lower-melting components (iodine number 53.6)

20 weight-percent higher-melting components (iodine number 39.7).

Example 3 40 kg. Congo palm oil (iodine number=51.3) were incompletely molten in a vessel equipped with a stirrer by heating to 35 C. Thereafter the material was passed within 2 hours through the scraper cooler arrangement described in Example 1 and thereby cooled down to 20 C. The ratio of the fat material in the scraper cooler and/ or storage vessel, respectively, amounted to 1:10. Upon reaching the temperature of 20 C., the fat material was left at this temperature for 2 hours and then emulsified in an equal volume quantity of a wetting agent solution, which contained 1 weight percent of a sodium soap of soyfatty acid and 3 weight percent of sodium sulfate. The dispersion was further treated as described in Example 1, and the following fractions were obtained:

33.2 kg.=83 weight-percent lower-melting components (iodine number 57.5)

6.8 kg.=17 weight-percent higher-melting components (iodine number 24.1).

Example 4 35 kg. of a somewhat solidified olive oil (acid number: 0.9; saponification number=l91; iodine number=70.8; transcontent=65%) was heated to 80 C. and then pumped through the apparatus described in the preceding examples. It was rapidly cooled, the temperature falling within one hour from 80 to 40 C. In this cooling no crystal separation took place. The cooling rate was slowed down so that within 10 hours a temperature of 28 C. was reached. During this time more and more crystals of the higher-melting components of the starting material were separated out. The temperature of the starting material in the next four hours was further decreased to 20 C. There was added to the fat material, which was being stirred continually in the storage vessel, 42 liters of wetting agent solution having a temperature of 20 C. The wetting agent solution contained 0.785 kg. of a paste of the alkylbenzolsulfonate described in Example 1 having 32 weight-percent active substance and 1.05 kg. sodium sulfate. Then the emulsion was pumped through the cooling system within 4 hours, being cooled to 12 C. The emulsion was maintained another 15 hours at this temperature. After separation of the dispersion in the centrifugal separator and separation of the aqueous phase from the higher-melting components of the starting material, the following fractions were obtained:

26.25 kg. solid components (iodine number 66.0; transcontent 67.5%)

8.75 kg. liquid components (iodine number 85.2; transcontent 58.5%).

When the sam starting material was continually cooled in the conventional manner over the same time interval and processed under otherwise similar conditions, the separation of the oil from the dispersion, in which the quantity of solid components is far greater than the quantity of liquid components, took place essentially more slowly.

Example As starting material there was employed a mixture of technical fat alcohols having an iodine number=72.5, which mixture consisted predominantly of oleyl and stearyl alcohol. 30 kg. of this mixture were pumped through the apparatus described in Example 1, being cooled within two hours from 40 to +6 C., whereby there was obtained a pasty mass permeated with crystals of solid fat alcohols. This mass was emulsified in 40 liters of an aqueous wetting agent solution, which contained 1 weightpercent of the sodium salt of a sulfation product of the technical fat alcohol serving as starting material and 3 weight-percent sodium sulfate. The dispersion was separated at '+6 C. in a centrifugal separator of the imperforate type into two phases. The lighter phase amounted to 73 weight-percent and consisted of the liquid components of the starting mixture. The aforesaid fraction had an iodine number of 92.5. From the aqueous phase there were isolated the solid components in an amount representing 27 weight-percent of the starting material. The iodine number of the solid constituents was 19.3.

Example 6 35 kg. tallow fatty acid (iodine number=52.5) in molten condition were pumped from a vessel equipped with a stirrer through a scraper cooler connected via an expansion line, as was described in Example 1. In the course of 24 hours the tallow fatty acid was cooled from 40 to C. There was then added 1.5 times the amount of the fatty material of an aqueous solution having the same temperature and containing 0.2% C -alkylsulfate and 1% MgSO while continuously stirring. The dispersion formed was then separated in a centrifugal separator. The following products were obtained:

58.7% olein '(iodine number 82.2; cloud point 5 C.) 41.3% stearin (iodine number 10.1).

When the same tallow fatty acid mixture was continually cooled in a vessel with stirrer, employing wall cooling, but otherwise processed under the same conditions, the stearin obtained had an iodine number of 17.2.

Example 7 35 kg. of a slightly solidfied olive oil (acid number: 0.9; saponification number :191; iodine number=70.8; transcontent=65%) were completely molten by heating to 80 C. and then so rapidly cooled by pumping through the apparatus described in Example 1 that the temperature of the glyceride in the storage vessel fell within 30 minutes to 35 C. At this temperature the crystallization began. Then the jacket of the scraper cooler was charged with water having a temperature of 38 C. and the fat further pumped therethrough. By the transfer of heat from the material in the storage vessel to the surroundings, the temperature of the material fell within the next two hours from 35 C. to 34 C. The amount of solid glyceride crystals separated during this time was about 10-20% of the amount of solid glycerides present at the finish of the entire cooling. After this condition was reached, the jacket of the scraper cooler was charged with water which was colder than the fat material being passed through the cooler. In this manner the temperature difference between the fat being passed through the cooler and the cooling agent was regulated so that after 20 hours a fat temperature of 20 C. was attained.

The fat in the storage vessel, which was being continually stirred, was then emulsified by the addition of a 1.5-fold by weight quantity of an aqueous wetting agent solution containing 0.7% of a sodiumalkylbenzolsulfonate (alkyl residue from tetrapropylene) and 3% sodium sulfate. The emulsion was brought by further pumping through the cooling system within 4 hours to 12 C. and kept for a further 16 hours at this temperature. Then the dispersion was separated in a centrifugal separator of the imperforate type into a lighter liquid glyceride phase (12 weight-percent, iodine number 83.4) and into a heavier aqueou phase having therein dispersed solid glyceride particles (88 weight-percent; iodine number 69.5; cloud melting point 35.8 C.; clear melting point 36.8 C.). The solid constitutents were usable as a cocoa-butter substitute.

In general, the invention may be used in the separation of different fatty materials, as fatty acids, fatty a1- cohols and esters of fatty acids or fatty alcohols. The term fatty materials designates compounds containing a higher fatty radical, this is to say an aliphatic straight or branched chain, saturated or unsaturated radical, preferably a hydrocarbon radical with 6-36, especially 10-28 carbon atoms.

We claim:

1. In the method for the separation of organic mixtures selected from the group consisting of mixtures of fatty acids, mixtures of fatty alcohols, mixtures of fatty acid esters and mixtures of fatty alcohol esters into components of different melting points by forming a dispersion of such a mixture in an aqueous solution of a surfaceactive material at a temperature at which the mixture contains both solid and liquid constituents and thereafter separating the aqueous dispersion into a specifically lighter phase of substantially liquid components of the mixture and a specifically heavier phase of aqueous medium with substantially solid components of the mixture suspended therein, the improvement which comprises cooling the said mixture in its entirety in successive steps from a temperature higher than the separation temperature down to the separation temperature and interrupting said cooling steps at least once with an intermediate stage in which substantially no cooling takes place, the ratio of the time of stay of said mixture in the cooling steps to the time of stay in the intermediate stage lies within the range of 200:1 to 1:200.

2. Method according to claim 1 wherein said mixture is in the form of an aqueous dispersion.

3. Method according to claim 1 wherein said mixture is in the form of a dispersion in an aqueous solution of a surface active material.

4. Method according to claim 1 which comprises effecting the cooling by the steps of cooling said mixture, maintaining said mixture in the following intermediate stage so that the time of stay of said mixture in said cooling step is from 4 to 200 times as great as in said intermediate stage and when a part of the mixture as higher melting component has solidified thereafter effecting the cooling so that the time of stay of said mixture in the subsequent intermediate stage is from 4 to 200 times as great as in the cooling step immediately preceding it.

5. Method according to claim 1, wherein the time of stay of said mixture in the intermediate stage is from 4 to 200 times as great as in the preceding cooling step.

6. Method according to claim 5, wherein the time of References Cited in the file of this patent stay of said mixture in the intermediate stage is from 10 UNITED STATES PATENTS to 50 tlmes as great as in the preceding cooling step.

7. Method according to claim 1, which comprise heat- 2,543,055 9 et 1951 ing said mixture in at least one of said intermediate stages. 5 2,800,493 Stem July 1957 8. Method according to claim 7, which comprises heat- 2,931,841 Devault P 1960 ing said mixture in said intermediate stage to substan- FOREIGN PATENTS tially the temperature of said mixture prior to the preced- 7 42,3 5 4 Great Britain Dec. 21, 1955 ing cooling step. 

1. IN THE METHOD FOR THE SEPARATION OF ORGANIC MIXTURES SELECTED FROM THE GROUP CONSISTING OF MIXTURES OF FATTY ACIDS, MIXTURES OF FATTY ALCOHOLS, MIXTURES OF FATTY ACID ESTERS AND MIXATURES OF FATTY ALCOHOL ESTERS INTO COMPONENTS OF DIFFERENT MELTING POINTS BY FORMING A DISPERSION OF SUCH A MIXTURE IN AN AQUEOUS SOLUTION OF A SURFACACTIVE MATERIAL AT A TEMPERATURE AT WHICH THE MIXTURE CONTAINS BOTH SOLID AND LIQUID CONSTITUENTS AND THEREAFTER SEPARATING THE AQUEOUS DISPERSION INTO A SPECIFICALLY LIGHTER PHASE OF SUBSTANTIALLY LIQUID COMPONENTS OF THE MIXTURE AND A SPECIFICALLY HEAVIER PHASE OF AQUOEUS MEDIUM WITH SUBSTANTIALLY SOLID COMPONENTS OF THE MIXTURE SUSPENDED THEREIN, THE IMPROVEMENT WHICH COMPRISES SUSPENDED THEREIN, THE IMPROVEMENT WHICH COMPRISES FROM A TEMPERATURE HIGHER THAN THE SEPARATION TEMPERATURE DOWN TO THE SEPARATION TEMPERATURE AND INTERRUPTING SAID COOLING STEPS AT LEAST ONCE WITH AN INTERMEDIATE STAGE IN WHICH SUBSTIANTIALLY NO COOLING TAKES PLACE, THE RATIO OF THE TIME OF STAY OF SAID MIXTURE IN THE COOLING STEPS TO THE TIME OF STAY IN THE INTERMEDIATE STAGE LIES WITHIN THE RANGE OF 200:1 TO 1:200. 